Electric induction apparatus



Feb. 13, 1945. e. CAMILLI ELECTRIC INDUCTION APPARATUS Filed Fb. 26, 1945 Invent- 3 (ilukgg lueh'no Camllll. b ,vw m

y His/Attorney Patented Feb. 13, 1945 ELECTRIC INDUCTION APPARATUS Guglielmo Camllll, Pittsfleld, Mass., assignor to General Electric Company, a corporation of New York Application February 26, 1943, Serial No. 477,251

'I provide a current and potential transformer 6 Claims.

My invention relates to an electric induction apparatus and particularly to a combination current and potential transformer.

It has been suggested to form a combination current and potential transformer by so arranging the core and coil components that the components of the current transformer are closely associated with the components of the potential transformer, as is described and claimed in patent application S. N. 477,329, filed February 26. 1943, to Kuechler, which is assigned to the same assignee as this present invention. In this Kuechler application a potential transformer structure is provided including a core member having a winding leg with high and low voltage windings surrounding the leg. Around the high voltage winding of the potential transformer there is provided a current transformer core member which has distributed therearound a high voltage current transformer winding. With this construction the potential transformer winding leg links the current transformer core and so as to prevent the potential transformer core from providing a short circuited turn linking the current transformer core a lateral discontinuity is provided in. the potential transformer core. The low voltage of the current transformer is provided by a number of turns which link the current transformer core and which also lie adjacent the surface or the potential transformer core. Such construction is not my invention and is hereby expressly disclaimed. J

.t is therefore an object of my invention to provide an improved and modified combination current and potential transformer of the type described above.

A further object of my invention is to pro vide an improved electric induction apparatus in which one of a plurality of. core members acts as a core member for one winding and a low voltage winding linking another core member.

Although I have shown and described particular embodiments of my invention, I do not desire to be limited to the particular embodiments described, and I intend in the appended claims to cover all modifications which do not depart from the spirit and scope of my invention.

In the drawing, Fig. l is aside view in partial section illustrating a combination current and, po= tential transformer which is provided with an embodiment of my invention, and Fig. 2 is a perspective view illustrating in detail the current and potential transformer component parts of the transformer illustrated in Fig. 1.

In the arrangements illustrated in the drawing,

winding is provided by a winding which links the current transformer core and which lies adjacent the potential transformer core. With this construction therefore the current transformer core attains a high voltage and therefore needs a minimum of insulation adjacent the high voltage windings of the current and potential transformer, and the current transformer core also acts as a shield for the potential transformer winding. Furthermore, the potential transformer core operates at a low voltage and is adjacent the low voltage current and potential transformer windings. In order, however, to provide a low voltage current transformer win-ding according to my invention I allow the potential transformer core to form a short cirouited turn linking the current transformer core. Thus the potential transformer core will have a circulating current passing through it proportional to the current flowing through the primary of the current transformer. Any suitable arrangement may be provided for making use of the current flowing through the potential transformer core which acts as a secondary winding of the current transformer such as by providing an auxiliary current transformer core with a linking secondary low voltage current transformer so as to step down the current flowing through the potential transformer core.

Referring more particularly to Fig. l of the drawing, it will be seen that i have provided a transformer including a casing to having a plurality of insulators it through which leads l3 and ill may pass. Also the insulators ll may act as an expansion chamber fora suitable insulating fluid such as oil which is placed inside the casing ll]. The casing lit encloses a potential transformer core is which may be of any suitable construction, such as a wound core. Linking a windlng leg to of the potential transformer core there is provided a low voltage potential transformer winding if and a high voltage potential transformer windin l t. These windings may be of any suitable construction such as concentric layer wound windings. The inner layer of the high voltage winding It may be grounded if desired through a lead I9, and the low voltage winding i! may be connected to any suitable metering device through the leads 2!].

The current transfcrmer construction is provided by a high voltage current transformer winding 25 which is distributed around a current transformer core 28. The core 28 may be of any suitabie'construction such as by winding a ribbon of magnetic material into a plurality of concentric convolutions.

This construction forms the subject matter of -the above-mentioned Kuechler application which also discloses a low voltage current transformer winding which links th current transformer core and which is placed adjacent the potential transformer core l5. This construction, however, imposes a large load on the current transformer because of relatively large lengths of conductor forming the current transformer secondary winding, and it will be seen that in the construetion as is shown in Fig. 2 the current transformer low voltage winding is provided by the potential transformer core l as this core provides a short circuited continuous turn linking the current transformer core 26. Furthermore, in order to be sure of a relatively low resistance continuous path I may provide a band 28 around the potential transformer core l5 which is held together by a bolt 29 which passes between shoulders 30 at each end of the .band. In order to provide a low resistance path for the current at the bolt a strap 3| may be brazed between the shoulders 30. It will, therefore, be seen that with this construction during operation of the apparatus a current will circulate through the potential transformer core I5 and the band 28 which is propontional to the current flowing through the primary winding 25 of the current transformer. Thus the potential transformer core I5 acts as a low voltage current transformer secondary winding. In order to step down the current flowing through the core iii, an auxiliary current transformer core 32 may be provided which links the potential transformer core I5. An auxiliary secondary current transformer winding may be provided through a winding 33 which links the auxiliary core member 3|. Leads 34 may be provided so that the winding 33 may be connected to any suitable metering device or relay system.

Although I have shown and described particu lar embodiments of my invention, I do not desire to be limited to the particular embodiments described, and I intend in the appended claims to cover all modifications which do not depart from the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A combination current and potential tran former including a potential transformer core,

potential transformer, windings surroundinga leg of said potential transformer core, a current transformer core around said potential transformer windings and said potential transformer winding leg, 2. high voltage current transformer winding around said current transformer core, said potential transformer core acting as a short circuited turn linking said current transformer core, and means linking said potential transformer core providing a low voltage current transformer winding.

2. A combination current and potential transformer including a potential transformer winding, a current transformer core, a high voltage current transformer winding linking said cur rent transformer core, and a potential transformer core linking said potential transformer winding and said current transformer core, said potential transformer cor providing a short circuited turn linking said current transformer core through which current may flow proportional to that flowing through said high voltage current transformer winding.

3. A combination current and potential transformer including a potential transformer winding, a current transformer core surrounding said potential transformer winding, 2. potential transformer core passing through a window in said potential transformer winding and providing a short circuited turn relative to said current transformer core, an auxiliary current transformer core linking said short circuited turn potential transformer core, and a low voltage current transformer winding linking said auxiliary core.

4. An electric induction apparatus including a potential transformer core, a potential transformer winding linking said core, a current transformer core linking said potential transformer core, a current transformer winding linking said current transformer core, said potential transformer core providing a short ci'rcuited turn relative to said current transformer core so that said potential transformer core acts as a secondary current transformer winding.

5. An electric induction apparatus including a potential transformer core, a potential transformer winding linking said core, a current trans former core linking said potential transformer core, a current transformer winding linking said current transformer core, said potential transfomer core providing a short clrcuited turn relative to said current transformer core, an auxiliary current transformer core linking saidpotential transformer core,'and a current transformer secondary winding linking said auxiliary core.

6. A combination current and potential transformer including a potential transformer core, a potential transformer winding surrounding a leg of said potential transformer core, a current transformer core coaxial with said potential winding, a high voltage current transformer winding around said current transformer core, said potential transformer core acting as a short circuited turn linking said current transformer core, and means electrically related with said potentialtransformer core providing a path for current flow proportional to that flowing through said high voltage current transformer winding.

'GUGLIELMO C AIMILLI. 

